Old 06-29-2020, 11:56 AM   #1
Evan
Human being with feelings
 
Join Date: Oct 2006
Location: Greece
Posts: 3,543
Default Speaker power consumption same as Watts? (silly question)

A silly question I've had since forever.

A speaker (monitor) has a stated amp of 100Watts.

Does that mean that it consumes 100Watts of power?

Does this depend on the volume set on the speaker?
Evan is offline   Reply With Quote
Old 06-29-2020, 12:32 PM   #2
Allybye
Human being with feelings
 
Join Date: Jan 2020
Posts: 140
Default

Quick answer No and Yes!

Amp power is rated maximum it can deliver -into a stated load, the speaker. For a powered speaker you can take it as it's max power delivered as the load is already fixed in the design.

Yes the power consumed depends upon the volume (as does the actual power delivered) but that is just one factor. Other factors that come into play are the waveform shape of what is being reproduced; the instantaneous i.e. short term waveform peak power as well as the low output quiet moments; the type of power amp with a class A being least efficient and other classes being more efficient such as class B; the type of power supply involved with a switched mode one being most efficient and a linear one being less efficient.

So it is complex but if you were to play something that delivered 100watts (electrical energy) then the power consumed from the mains or battery supply would be more than that (lack of efficiency doing the conversion)...but the audio power (the actual air sound waves) would be very much less.

For that latter the transponder i.e. the speaker doing the conversion from it's input power to moving air as it's output..... is exceedingly inefficient!!
Allybye is offline   Reply With Quote
Old 06-29-2020, 12:37 PM   #3
Allybye
Human being with feelings
 
Join Date: Jan 2020
Posts: 140
Default

p.s. question from me....How is the virus doing now in Greece? Last I heard very low but that was before opening up to tourists.
Ευχαριστο
Allybye is offline   Reply With Quote
Old 06-29-2020, 12:53 PM   #4
karbomusic
Human being with feelings
 
karbomusic's Avatar
 
Join Date: May 2009
Posts: 26,298
Default

Watts always = heat in some form.

Just an aside that watts for the speaker spec itself (not the amp) is how much heat it can handle before failure due to that heat.

The rule of thumb is you need the nomimal or program number, and the peak number. The speaker can handle a much higher transient peak because that's not heating the voice coil. Usually you want the amp to run a something lower than it's rating for nominal, leaving enough headroom to handle those peaks.

It's debated to this day but EV used to evangelize clipping an amp causing speakers to heat more, thusly under powering being more dangerous than a properly sized amp. There is a thought experiment there, since clipping starts producing a square wave, this means the voice coil is not moving in and out as much - which is the primary way it cools itself. Those squared peaks are essentially DC, heating the coil FWIW.

I spent a week at EV in Minnesota 20 years ago and hung out with their designers, though I can't for the life of me remember the above conversation (I brought it up to them at the time because it did and didn't make sense).

Lastly, how loud a speaker gets isn't really about watts but about how efficient they are.
__________________
There are no problems, only solutions. - John Lennon
karbomusic is offline   Reply With Quote
Old 06-30-2020, 09:45 AM   #5
ashcat_lt
Human being with feelings
 
Join Date: Dec 2012
Posts: 4,957
Default

Pretty sure the OP has a powered speaker and wants an idea of how much juice that’s going to pull out of the wall. The answer is that the stated amplifier output wattage is not a good indicator of its wall-power consumption. Most gear will have a separate specification for that consumption. If it’s not on the actual spec sheet, it’s often printed on the chassis near the power cable itself. That too will be a rated maximum and probably more than what it will actually use in practice, but if you want this to help figure out how much power capacity you’re going to need from things upstream, you should probably double it for safety’s sake.

But...
Quote:
Originally Posted by karbomusic View Post
It's debated to this day but EV used to evangelize clipping an amp causing speakers to heat more, thusly under powering being more dangerous than a properly sized amp.
The idea is that a clipped amp will blow speakers even when they’re not themselves near their limits while they might survive a clean amp trying to push them too far for a little while. Overpowering a speaker will usually make it sound bad way before it causes permanent damage while clipping the amp could just kill the speaker before you get a chance to go “oh hey that’s clipping...” Or that’s the story anyway.

My personal opinion is that you should just make sure that the whole thing will be way too loud before you have to worry about either issue. “It’s only too loud if the system is underspecified.”
ashcat_lt is offline   Reply With Quote
Old 06-30-2020, 10:22 AM   #6
karbomusic
Human being with feelings
 
karbomusic's Avatar
 
Join Date: May 2009
Posts: 26,298
Default

Quote:
Originally Posted by ashcat_lt View Post
But...

The idea is that a clipped amp will blow speakers even when they’re not themselves near their limits while they might survive a clean amp trying to push them too far for a little while. Overpowering a speaker will usually make it sound bad way before it causes permanent damage while clipping the amp could just kill the speaker before you get a chance to go “oh hey that’s clipping...” Or that’s the story anyway.

My personal opinion is that you should just make sure that the whole thing will be way too loud before you have to worry about either issue. “It’s only too loud if the system is underspecified.”
Yea, I know for the under-powering as I was explaining (though many take issue with that idea)... but for the overpowering part, IME they sound fantastic right before they blow - ask me how I know.
__________________
There are no problems, only solutions. - John Lennon
karbomusic is offline   Reply With Quote
Old 06-30-2020, 11:00 AM   #7
ashcat_lt
Human being with feelings
 
Join Date: Dec 2012
Posts: 4,957
Default

I mean we do all kinds of horrible things to guitar speakers. For monitors and PAs and the like, though, it’s best to just have more than you’re going to want so you never have to find the limits.
ashcat_lt is offline   Reply With Quote
Old 06-30-2020, 03:01 PM   #8
Allybye
Human being with feelings
 
Join Date: Jan 2020
Posts: 140
Default

The speaker blowing issue is related to Karbo's heater analogy!

Music, even that horrid distorted compressed stuff often produced (oops!) is composed of lots of a variety of sine waves that vary widely from their peak values to a lot lower (even a few dB is a significant change of power) and the average power (r.m.s) is be generally a lot lower than max and high that only have short durations.

However clipped output, as it clips harder and harder, approaches a square wave and the power rises significantly thus heating more and more then 'pop'....or not as the speaker coil fuses! Often it's the tweeter that is most at risk!

Just driving too hard unclipped just results in limited excursions of the cone and other complex wobblings!!

As a little interesting aside some music has a power that approaches that of a static value sine wave...such as bagpipes!
Allybye is offline   Reply With Quote
Old 07-01-2020, 02:08 AM   #9
Softsynth
Human being with feelings
 
Softsynth's Avatar
 
Join Date: Jun 2015
Posts: 6,196
Default

Hard clipping sounds ugly but oddly enough gently distorted signals are your ears friends. The human ear perceives distortion as loudness. This is why weedy ghetto blasters seem annoyingly loud in close quarters with just a few watts, and in reality aren't playing all that loud. In contrast large and genuinely high quality monitors and Hi-fi systems can play loud and sound clean, so you need to be wary of playback levels. This applies even more to quality headphones as the diaphragms barely have to move to produce sound and are incredibly well controlled thus produce very little distortion.

This distortion is also why we perceive more bass from small speakers. Clean bass from big systems in large listening rooms (and the best high-end headphones) is qualitatively superior so you have to be even more wary the better your system gets.

The OP should get a power measuring wall plug with LCD to see how much power he is really using at typical listening levels.
Most music we listen to typically happens in the first watt, but of course speaker systems are less efficient than that.

Last edited by Softsynth; 07-01-2020 at 02:56 AM. Reason: Smartphone typos..
Softsynth is offline   Reply With Quote
Old 07-03-2020, 02:25 AM   #10
Evan
Human being with feelings
 
Join Date: Oct 2006
Location: Greece
Posts: 3,543
Default

Thanks all for the replies!

Quote:
Originally Posted by Allybye View Post
p.s. question from me....How is the virus doing now in Greece? Last I heard very low but that was before opening up to tourists.
Ευχαριστο
Yes, it seems to be pretty much under control at the moment... average number of new confirmed daily cases 10-20. Deaths are at 0 or sometimes 1 daily. Flights have just opened for tourists so we'll see how this turns out.
Evan is offline   Reply With Quote
Old 07-03-2020, 02:33 AM   #11
Allybye
Human being with feelings
 
Join Date: Jan 2020
Posts: 140
Default

Thanks Evan.
Great that new case rates are so low and even better if zero but realistically a figure to be envied with that size of population. I hope that is on the back of lots of testing and not just those taking ill!
Allybye is offline   Reply With Quote
Old 07-03-2020, 06:01 AM   #12
Evan
Human being with feelings
 
Join Date: Oct 2006
Location: Greece
Posts: 3,543
Default

Quote:
Originally Posted by Allybye View Post
I hope that is on the back of lots of testing and not just those taking ill!
There is testing, but I don't know if it's enough. There's also random sample testing of tourists coming in the country now.

The death count is generally on constant decline (despite cases) in the northern hemisphere. Probably due to summer/sun/vitamin D/a more benign mutation of the virus? (who knows).

We're totally off topic of course but... given the importance of this pandemic, it's alright.
Evan is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -7. The time now is 11:57 AM.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2020, vBulletin Solutions Inc.